Patent GB-1305397-A (GB)
IPC: D04H1/4334
Filed: 1970-01-16
Abstract: 1305397 Preparing and treating fibres; spinning and testing yarns DU PONT OF CANADA Ltd 16 Jan 1970 2313/70 Headings D1F DIN and D1W In a process for converting a mass of filaments consisting of undrawn cold-drawable continuous and/or long filaments of synthetic polymer or partially drawn, perhaps tangled waste material thereof to a uniform filamentary mass (which may, for example, be subjected to conventional preparatory treatments, cut into staple lengths and formed into sliver which is spun into yarn) usually of filaments of various lengths which have been drawn but have both undrawn segments and crimps in random directions spaced randomly along the lengths thereof, the initial mass is subjected to successive steps of forwarding at a low speed under restraint; withdrawing at high speed e.g. with opening needles located at the periphery of a rotating cylinder adapted to separate the filaments; cooling e.g. by the flow of air caused by the rotating cylinder; stretching in random manner, as by the action of pulling the filaments down to the base of the needles as the cylinder rotates; optionally, combing as by rigid combs attached to the periphery of the cylinder; collecting, perhaps including blowing filaments which have been crimped by the stretching and/or combing operations away from the cylinder by the flow of air. The mass may include bicomponent or cospun filaments of various cross-section, including trilobal and "dog-bone" shape, of polyamide, polyethylene terephthalate, polypropylene, polyvinyl alcohol and/or polyvinyl chloride. A final staple fibre product may be blended with natural e.g. cotton or wool, or synthetic fibres. The crimp is compound and may include single loops or curls at the ends of the filaments due to recoil upon stretch-breaking. Conversion apparatus. In the machine shown, the initial mass evenly spread upon and fed by an apron 10 is received and uniformly advanced by fluted, feed, guide and pressing rollers 13, 14, gathered and stretched by the garnett wire covered roller 17 which cooperates with similarly covered rollers 18, 21, and clearing roller 23 (two of which are loaded and the teeth of two of which point oppositely to their direction of rotation) to impose restraint on the fibrous material as it is gathered by sharp pointed needles 34 on a cylinder 25 rotating at a constant selected speed. As shown in Fig. 3, staves 33 on the cylinder carry rows of filament piercing, randomly separating, straightening and randomly stretching primary needles 34 inclined e.g. at 45, to the direction of travel, and combs, as at 35, comprising teeth 36 slanting in opposite directions alternately around the cylinder periphery: alternatively or additionally, combs may be mounted on each or some trailing edge(s) of the staves and all combs perform a shredding action on the fibrous material and assist in stretching, crimping (by knife-edge effect) and breaking filaments and also roughen the surfaces thereof. Material passing over the cylinder 35 is forced towards the base of needles 34 as a result of pressure of the air which enters the casing 37 through intake 40. The resultant high velocity flow of air cools the filaments (which become heated by the mechanical treatments, especially stretching) and removes the product mass of filaments through a volute discharge outlet of the casing 37. More than one pass of the material through the machine or passage through succeeding such machines may be necessary to achieve a desired product B. Liquid and/or heat treatments. The initial material may be lubricated by an antistatic or fibre lubricating agent or an emulsion of both applied as by spraying successive batches or layers or by an air pressure spray nozzle system (not shown) above the apron 10. The filaments being drawn may be softened and/or strengthened by heating directly by applied "live" steam or hot air or by electric elements in one or more feed rollers: thus, steam supply pipes may be positioned between feed rollers 13, 17 and 18 and between roller 21 and cylinder 25, Fig. 5 (not shown) the roller 23 then being redundant since the steam also effects clearing. Testing. Transverse dimension of selected filaments is measured (for deviation tests) by projecting an interference pattern, caused by the filament on a laser beam, onto a calibrated screen.